The systemic, particularly cardiovascular, manifestations of acute brain injury from any cause are important causes of morbidity and mortality and may be modifiable. Many workers have shown that the autonomic response to brain damage may be important in causing the cardiovascular manifestations and we seek to continue our investigations of this relationship. By simultaneously following the metabolic, specifically catecholamine, and cardiovascular changes following acute brain damage we hope to better define the incidence, clinical presentation and importance of the systemic alterations which do occur. In this way we will better understand the mechanisms relating to these manifestations and their possible modifications by appropriate agents.